Enhancing physico-mechanical and antibacterial properties of natural rubber using synthesized Ag-SiO2 nanoparticles

Enhancement in antimicrobial efficacy and biodegradation of natural rubber latex through graphene oxide/nickel oxide nanoparticles

This work aims to fabricate antibacterial natural rubber latex composites by introducing different ratios of graphene oxide (GO) and nickel oxide (NiO) nanoparticles. The nanocomposites were prepared using latex mixing and a two-roll mill process, followed by molding with a heating hydraulic press. Detailed analyses were conducted to evaluate the rheological, chemical, physical, thermal, mechanical, and electrical performance of the composites. Fourier transform infrared spectroscopy (FTIR) was employed to analyze the interaction among different components, while the surface morphology was examined through the field emission scanning electron microscopy (FESEM) technique. The composites with a loading ratio of 1:2 of GO to NiO (optimized concentration) exhibited the highest tensile strength (24.9 MPa) and tear strength (47.4 N/ mm) among all the tested samples. In addition, the composites demonstrated notable antimicrobial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. The thermal stability of the composites was observed up to 315 °C, and their electrical resistivity lies in the insulating range across a temperature span of 25 °C to 50 °C. The research uncovers critical insights into advancing composite materials suitable for diverse applications, featuring inherent antibacterial attributes, robust mechanical properties, resilience to solvent, UV shielding properties, and controlled electrical resistivity capabilities.

Unveiling the silver lining: examining the effects of biogenic silver nanoparticles on the growth dynamics of in vitro olive shoots

The current study aimed to evaluate the effects of biogenic silver nanoparticles (AgNPs) on growth behavior and leaf anatomy of in vitro growing shoots of 'Picual' and 'Dolce' olive cultivars. Biosynthesis of AgNPs was carried out using the cell-free filtrate of Fusarium oxysporum. The dimension and shape of the synthesized AgNPs have been analyzed using spectroscopy and topography analysis tools, confirming that the biosynthesis of AgNPs is a crystalline nanostructure with an average particle size of 37 nm. The shoots of the selected olive cultivars were cultured on Rugini olive medium-supplemented AgNPs at 0, 10, 20, and 30mg L- 1. The effect of genotypes on shoot multiplication was significant, 'Picual' recorded higher values of shoot growth parameters compared with 'Dolce' cultivar. Adding AgNPs to the culture medium significantly affected the growth of in vitro olive shoots. AgNPs at 20 and 30mg L- 1 produced higher values of the number of shoots, shoot length, and leaf number of Picual cv. compared with the control treatments, but the higher AgNPs concentration harmed the growth parameters of Dolce cv. and recorded lower growth values compared with the lower concentration (10mg L- 1). AgNPs had a significant effect on leaf morphology and their anatomical structure. The current results showed that the stimulatory effect of AgNPs on shoot growth of in vitro olive shoots is highly dependent on plant genotype and nanoparticle concentration.

Wormwood-infused porous-CaCO3 for synthesizing antibacterial natural rubber latex

Wormwood leaf is a traditional Chinese herbal medicine with a high medicinal value and long application history and its essential oil is a high-purity plant oil extracted from Wormwood leaf. Pharmacological research reveals that Wormwood leaf and Wormwood essential oil are a broad-spectrum antibacterial and antiviral drug, which can inhibit and kill many bacteria and viruses. We loaded wormwood extract on porous calcium carbonate (Porous-CaCO3) and introduced it and Wormwood essential oil into Natural rubber latex (NRL), thus synthesizing NRL composites with excellent vitro and in vivo antibacterial effect, cell compatibility and mechanical properties. This NRL material can delay the light aging and thermal oxidation of some mechanical properties, which provides a broader avenue for its commercialization.

A combined treatment of Proteinase K and biosynthesized ZnO-NPs for eradication of dairy biofilm of sporeformers

Biofilms of sporeformers found in the dairy industry are the major contaminants during processing, as they withstand heat and chemical treatment that are used to control microbes. The present work is aimed to remove these resistant forms of bacterial community (biofilm) present in dairy production lines using ecofriendly agents based on proteinase K (Prot-K) coupled with Zinc oxide nanoparticles (ZnO-NPs). Some metal/metal oxide (Ag, CuO and ZnO) NPs were prepared microbially, and ZnO-NPs were characterized as the most effective ones among them. The produced ZnO-NPs were 15-25 nm in size with spherical shape, and FTIR analysis confirmed the presence of proteins and alkanes surrounding particles as capping agents. Application of Prot-K for eradication (removal) of a model biofilm of mixed sporeformers on food-grade stainless steel resulted in an 83% reduction in the absorbance of crystal violet-stained biofilm. When Prot-K was mixed with the biosynthesized NPs ZnO_G240, the reduction increased to 99.19%. This finding could contribute to an efficient cleaning approach combined with CIP to remove the recalcitrant biofilms in dairy production lines.

Application of Ag@SiO2 nanoparticles within PVA to reduce growth of E. coli and S. aureus in beef patties

To overcome defects of polyvinyl alcohol (PVA) and expand its applications in food preservation, PVA/Ag@SiO₂ nanocomposite films were prepared using the solution intercalation film-casting method. Transmission electron microscopy, X-ray diffraction, and UV-visible absorption spectra were applied to confirm the synthesis of the nanoparticles (NPs). Effects of Ag@SiO₂ NPs on physicochemical characteristics of films like viscosity, swelling ratio, tensile strength, elongation at break, as well as antibacterial activity were also evaluated. Results indicate that Ag@SiO₂ NPs could be synthesized successfully, and the increasing concentration of Ag@SiO₂ NPs led to the decrease in viscosity and the swelling ratio of the PVA/Ag@SiO₂ NPs nanocomposite films. PVA/Ag@SiO₂ nanocomposite films exhibited increased tensile strength and strong antibacterial activity against Escherichia coli and Staphylococcus aureus. The films had higher antibacterial activity toward E. coli compared with S. aureus. Beef patties were applied to verify the practicality of PVA/Ag@SiO₂ films. PVA/Ag@SiO₂ NPs nanocomposite films act as an active food packaging system showing great potential in retaining food safety and prolonging the shelf-life of packaged foods. PRACTICAL APPLICATION: During the storage of fresh meat, the microbial count on the meat surface increased with increasing storage time; meat proteins could be broken down by microorganisms, causing the tissue structure to be destroyed, leading to loose muscle fibers and loss of nutrient-containing juices. In this paper, by improving the PVA film, a new antibacterial membrane was prepared, which can be used for fresh meat sold in supermarkets, as a lining at the bottom of the meat or directly covering the meat. The method can significantly decrease the number of microorganisms and extend the shelf-life of fresh meat.

Isolation of Haematococcus lacustris as source of novel anti-multi-antibiotic resistant microbes agents; fractionation and identification of bioactive compounds

In this work, freshwater microalga, Haematococcus lacustris was isolated from the River Nile, identified and deposited in genebank under name of H. lacustris isolate REH10 with accession number OK336515. N-hexane extract was produced high inhibition effects against multi-antibiotic resistant pathogens. The n-Hexane extract was fractionated and 2 fractions (F3 & F4) exhibited high antibacterial activity (15 - 20 mm) compared with other fractions. Thus, they sub-fractionated and 2 sub-fractions produced from the F3 had high inhibition activity against all tested pathogens (18-20 mm). To identify the main compounds responsible for inhibition growth of multi-drug resistance bacteria, GC-MS chromatogram analyses was applied on the F3 and its sub-fractions 2 and 3. Five compounds detected in the 2 sub-fractions. Palmitic acid was identified as the first report antibacterial agent. The antioxidant activity of SF3-3 was reached to 86 and 80.5% for DPPH and ABTS.⁺ tests, respectively.

An Overview on the Recent Advances in the Treatment of Infected Wounds: Antibacterial Wound Dressings

A wound can be surgical, cuts from an operation or due to accident and trauma. The infected wound, as a result of bacteria growth within the damaged skin, interrupts the natural wound healing process and significantly impacts the quality of life. Wound dressing is an important segment of the skincare industry with its economic burden estimated at $ 20.4 billion (in 2021) in the global market. The results of recent clinical trials suggest that the use of modern dressings can be the easiest, most accessible, and most cost-effective way to treat chronic wounds and, hence, holds significant promise. With the sheer number of dressings in the market, the selection of correct dressing is confusing for clinicians and healthcare workers. The aim of this research was to review widely used types of antibacterial wound dressings, as well as emerging products, for their efficiency and mode of action. In this review, we focus on introducing antibiotics and antibacterial nanoparticles as two important and clinically widely used categories of antibacterial agents. The perspectives and challenges for paving the way for future research in this field are also discussed. This article is protected by copyright. All rights reserved.

Novel fabrication of SiO2/Ag nanocomposite by gamma irradiated Fusarium oxysporum to combat Ralstonia solanacearum

The bacterial wilt is a global destructive plant disease that initiated by the phytopathogenic Ralstonia solanacearum. This study display a novel biofabrication of silica/silver nanocomposite using Fusarium oxysporum-fermented rice husk (RH) under solid state fermentation (SSF). The biofabricated nanocomposite was characterized by XRD, UV–Vis. spectroscopy, DLS, SEM, EDX elemental mapping, and TEM analyses as well as investigated for anti-R. solanacearum activity. Response surface methodology was also processed for optimizing the biofabrication process and improving the anti-bacterial activity of the fabricated nanocomposite. Maximum suppression zone of 29.5 mm against R. solanacearum was reached at optimum RH content of 6.0 g, AgNO₃ concentration of 2.50 mM, reaction pH of 6.3, and reaction time of 2 days. The anti-R. solanacearum activity of the fabricated nanocomposite was further improved by exposing the F. oxysporum strain to a gamma irradiation dose of 200 Gy. In conclusion, RH recycling under SSF by F. oxysporum could provide an innovative, facile, non-expensive, and green approach for fabricating SiO₂/Ag nanocomposite that could be applied efficiently as an eco-friendly antibacterial agent to combat R. solanacearum in agricultural applications. Moreover, the developed method could serve as a significant platform for the designing of new nanostructures for broad applications.

Biofabricated SiO₂/Ag nanocomposite by gamma irradiated-F. oxysporum under SSF.

Statistical optimization and complete characterization of SiO₂/Ag nanocomposite.

Application in agriculture for combating the wilt causing R. solanacearum.

High antibacterial and barrier properties of natural rubber comprising of silver-loaded graphene oxide

The antibacterial and barrier properties of natural rubber used as gloves are very important for the safety of medical staffs. In this research, the silver (Ag) particles were loaded on the surface of graphene oxide (GO) first modified by polydopamine (PDA). Then, the complex particles (Ag-PDA-GO) were introduced into the natural rubber (NR) latex, and the Ag-PDA-GO/NR film composites were obtained by the dipping method. Results showed that a fine dispersion of Ag-PDA-GO in NR film was obtained due to the isolation effect of Ag and PDA between GO sheets. Compared with those of pristine NR composite, when the GO content was only 0.2 phr, the tensile strength, tear strength and modulus at 100% and 300% strains of the composites increase by 66.7%, 128%, 37.7% and 30.7%, respectively, compared with the pure NR. The gas diffusion coefficient was reduced by 15.6% due to the strong interface interaction between GO and NR macromolecules. When the GO content was only 0.1 phr, the minimum inhibitory concentrations (MIC) of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were 16 and 32 μg/mL, respectively. These results are of great significance for improving the barrier and antibacterial properties of medical rubber products.

Improving the bioremediation technology of contaminated wastewater using biosurfactants produced by novel bacillus isolates

Biosurfactants have many advantages outside chemical one, led for application it through different sectors. So, the present study aimed for improving the bioremediation technology of contaminated wastewater using biosurfactants produced by novel bacillus isolates. In this regard, Bacillus thuringiensis and Bacillus toyonensis strains were obtained as most producing isolates of highly active biosurfactants. The optimized conditions for high biosurfactants yield production were established. Also, the stability of the produced biosurfactants at various conditions, pH, temperature and salinity was studied. The biosurfactant has been reported up to 120 °C, pH 12 and 10% of NaCl. The identified biosurfactants, decanoic acid and oleamide were applied for wastewater remediation from oil residues and pathogens contamination. The biosurfactant was had high antibacterial activity compared with references antimicrobial drugs, as well as it is enhanced bioremediation technology for petroleum oil residues contaminating sites. Thus, we can say, these biosurfactants could achieve the objectives of sustainable development.